This invention relates to a method of winding armatures for revolving-field electrical machines and more particularly to an improved winding method that permits a greater coil density to be obtained and avoids the likelihood of damaging the wire by the winding needle during the winding operation and also coils that are wound around skewed pole teeth.
Various methods have been employed for forming the coil windings for the armature of rotating electrical machines such as motors or generators. Generally these winding methods result in somewhat complicated structures and structures wherein the maximum coil densities are not capable of being obtained. Several of these methods involved passing a needle in the slot between the extending cores of the armature and then having that needle circumscribe the individual cores so as to form the windings. Because of the fact that the needle must be passed in the space between the cores, room must be left for it and this decreases the coil density.
In addition, there is a likelihood that the needle may engage already wound coils and damage them particularly by removing their insulation. These various prior art methods are described in full detail in the co-pending application assigned to the Assignee hereof, entitled xe2x80x9cStator Coil Structure For Revolving-Field Electrical Machine and Method Of Manufacturing Samexe2x80x9d, application Ser. No. 09/683764, filed Feb. 12, 2002.
Even greater difficulties arise when the pole teeth and interposed slots are skewed relative to the axis of rotation of the associated machine. This expedient of skewing the pole teeth is frequently done to prevent cogging generated when the magnets opposed to the plural magnet pole teeth disposed side by side pass between the magnet pole teeth. Conventional winding machines do not permit the winding needle to traverse the pole teeth because of the skewed teeth and slots. If this were to be attempted the pole teeth would interfere with the path of the winding needle. Because of this such coils have been manually wound thus increasing the machine cost.
It is, therefore, a principle object of this invention to provide an automatic winding method and apparatus for winding the coils on a rotating electrical machine having skewed armature teeth.
It is a further object of this invention to provide such a method and apparatus where the coil density can be substantially increased by keeping the winding needle substantially out of the slots between the teeth during the winding operation.
A first feature of this invention is embodied in a method of winding the coils of a rotating electric machine comprising a circular core of a magnetic material and a plurality of magnetic pole teeth extending radially from the circular core wherein each of the magnetic pole teeth defining a core and slots formed between adjacent magnetic pole teeth. Each of the slots defines a mouth formed between adjacent outer ends of the cores. The pole teeth and the slots are skewed relative to the axis of rotation of the rotating electric machine so that the slots have the shape of a parallelogram in a developed plan view. The winding method comprising the steps of positioning a threading needle having an opening through which the wire for winding the coils is fed in proximity to one of the mouths. Relative movement of the needle and pole tooth is caused to effect movement of the needle opening in a path around one of the pole teeth at one side of slot without moving the needle in any substantial distance along the length of the one pole tooth to form a first winding. The relative movement of the needle and pole tooth is continued to effect movement of the needle opening in a path around one of the pole teeth at one side of slot without moving the needle in any substantial distance along the length of the one pole tooth to form succeeding windings each of which moves the previous winding along the pole tooth toward the circular core without requiring movement of the needle in any substantial distance along the length of the one pole tooth so that the needle need not be moved any substantial distance into the slot.
A further feature of the invention is adapted to be embodied in an apparatus for performing the aforenoted method. This apparatus comprises a threading needle having an opening through which the wire for the winding the coils is fed in proximity to one of the mouths. A support supports the circular core. A drive operates the support and said winding needle being for effecting relative movement of the needle and pole tooth to effect movement of the needle opening in a path around one of the pole teeth at one side of slot without moving the needle in any substantial distance along the length of the one pole tooth to form a first winding and continuing the relative movement of the needle and pole tooth to effect movement of the needle opening in a path around one of the pole teeth at one side of slot without moving the needle in any substantial distance along the length of the one pole tooth to form succeeding windings each of which moves the previous winding along the pole tooth toward the circular core without requiring movement of the needle in any substantial distance along the length of the one pole tooth so that the needle need not be moved any substantial distance into the slot.